     XBack = {};
    (function (XBack) {
        XBack.STATE = 'x - back';
        XBack.element;

        XBack.onPopState = function (event) {
            event.state === XBack.STATE && XBack.fire();
            XBack.record(XBack.STATE); //初始化事件时，push一下  
        };

        XBack.record = function (state) {
            history.pushState(state, null, location.href);
        };

        XBack.fire = function () {
            var event = document.createEvent('Events');
            event.initEvent(XBack.STATE, false, false);
            XBack.element.dispatchEvent(event);
        };

        XBack.listen = function (listener) {
            XBack.element.addEventListener(XBack.STATE, listener, false);
        };

        XBack.init = function () {
            XBack.element = document.createElement('span');
            window.addEventListener('popstate', XBack.onPopState);
            XBack.record(XBack.STATE);
        };

    })(XBack); // 引入这段js文件  监听android后退